This invention relates to a rotary stacker and method and, more particularly, to a stacker useful in packing a sequence of web units (such as napkins) into a stack.
In the past, stacking of napkins, for example, has been achieved through the use of reciprocating movement (U.S. Pat. No. 1,845,895) or orbital movement (U.S. Pat. Nos. 3,740,049; 4,349,185; 4,625,957). These were speed limiting because the packer fingers or plunger had to move out of the way before another unit could be packed. With even the fastest packer mechanisms, a discrete time was involved after the packer mechanism had reached the end of its "throw", i.e., bottom dead center.
According to the invention, this discrete time lag no longer is present. The plurality of cam means of the invention is "out of the way" virtually simultaneously with the end of the throw. Moreover, the invention provides an additional new result not heretofore possible: while the next succeeding unit is entering the packing area, the preceding units are held down by some of the cam means downstream of the path of travel of the units into the packing area. And this advantageous "hold-down" pertains right up to the time another packing cycle starts.
Other objects and advantages of the invention may be seen in the ensuing specification.